1. Field of Invention
This invention relates to a pencil eraser of rubber or plastic material serving as the writing end statically affixed cowling sleeve of a double acting mechanical pencil, through which extends and retracts the frustum shaped segment and lead sleeve of the mechanical pencil, and to a ball point pen eraser of rubber or plastic material serving as the writing end statically-affixed cowling sleeve of a single acting ball point pen utilizing erasable ink, through which the ball point and ink feeding tube extends and retracts.
2l. Description of Prior Art
Both mechanical and conventional wood pencils have, for many years, been adapted to provide an attached eraser at the end of the cylindrical pencil barrel opposite that from which the pencil lead extends. Conventional wood pencils typically are provided with a non-renewable and non-adjustable eraser attached by means of a cylindrical band and sized such that the exhaustion of the usable portion of the eraser will coincide with the life of the pencil as it is used and resharpened.
Mechanical pencils, on the other hand, have a virtually unlimited life by virtue of replacement pencil leads. As a result, mechanical pencils are sometimes provided with some sort of adjustable eraser mechanism and replacement erasers at the non-writing ends of the pencils. Examples of these eraser adjustment mechanisms can be found in U.S. Pat. Nos. 1,671,393; 3,072,101; 3,099,251; and 4,352,580. Each of the above listed U.S. Patents provides a unique type of adjustment mechanism to facilitate extension of additional portions of an eraser at the non-writing end as it is consumed in normal use.
U.S. Pat. No. 1,473,090 to Ferry (1923) discloses a circular sleeved eraser assembly mounted on the outside of a plain lead pencil, through which the writing end of the pencil protrudes, and which places the eraser in close proximity to the lead point. A sliding of the assembly forward places the eraser segment at and beyond the lead point of the pencil for erasure of written material.
This eraser assembly suffers several disadvantages: the assembly at the writing end unbalances the pencil, obscures the point of the pencil and the written material, is subject to relatively easy loss or mislocation, and is a meaningful obstruction to placement in a pocket.
U.S. Pat. No. 4,899,419 to Saleen (1990) discloses a circular, sleeved eraser eraser assembly similar in intent to that of U.S. Pat. No. 1,473,090 to Ferry (1923), but for use with a mechanical pencil, and suffers the same several disadvantages noted above.
None of the above listed attempts to provide maximum convenience to the user of a conventional or mechanical pencil eraser has succeeded in making the application of the eraser almost as easy or convenient as the application of the lead point.
It is the object of this invention to do just that, and to do so with a device which is inexpensive and simple to manufacture